Slow b43 with 2.6.25.9 on an asus wl-700ge home-router

Slow b43 with 2.6.25.9 on an asus wl-700ge home-router

[Stefan Monnier]

I finally started to use the b43 driver on my home-router and am happy
to have it working at all (with WPA), but I notice that the speed is
pretty terrible: I cannot seem to get more than 100KB/s out of it (I
use it as a personal web proxy, so it ends up slowing down my
web-surfing :-( ).

Originally "iwconfig" told me that the bit rate was 2Mb/s (and even
that should allow me to get a bit more than 100KB/s).
After "iwconfig wlan0 rate 54M", the result is the same (except that
"iwconfig" tells me the bit rate is 54Mb/s).

More specifically, iwconfig tells me things like:

wlan0     IEEE 802.11  ESSID:"test"  
          Mode:Managed  Frequency:2.457 GHz  Access Point: 00:10:30:C0:50:50   
          Bit Rate=54 Mb/s   Tx-Power=27 dBm   
          Retry min limit:7   RTS thr:off   Fragment thr=2352 B   
          Link Quality=95/100  Signal level:-54 dBm  Noise level=-63 dBm
          Rx invalid nwid:0  Rx invalid crypt:0  Rx invalid frag:0
          Tx excessive retries:0  Invalid misc:0   Missed beacon:0

which seems to indicate that the reception is indeed good.
Any idea what I might want to check?

I did notice that my dmesg says things like
"received packet with  own address as source address".  This seems
related to my use of bridging, but:
1 - I have no bridging loop (actually I unplugged all ethernet cables,
    so the only active network interface in the bridge is wlan0).
2 - taking wlan0 out of the bridge eliminates those messages, but
    doesn't improve the bandwidth.

Any idea what might be going on?


        Stefan

Re: Slow b43 with 2.6.25.9 on an asus wl-700ge home-router

[Michael Buesch]

On Wednesday 09 July 2008 07:50:11 Stefan Monnier wrote:
> Any idea what might be going on?

Yeah well. It's a bug somewhere. I didn't have time to track it down, yet.
I have no idea where it is and what kind of bug it is. Pretty time
consuming job. So if you can do a patch that fixes it, I will take it. ;)

-- 
Greetings Michael.

Re: Slow b43 with 2.6.25.9 on an asus wl-700ge home-router

[Stefan Monnier]

>> Any idea what might be going on?
> Yeah well.  It's a bug somewhere.

The scary part is that there's only Free Software involved, AFAICT.
That *should* be bug-free, shouldn't it?

> I didn't have time to track it down, yet.

Does that mean that you know about the problem and can reproduce it?

> I have no idea where it is and what kind of bug it is. Pretty time
> consuming job. So if you can do a patch that fixes it, I will take it. ;)

Having too much time on my hand, and being naturally brilliant, I just
came up with the obvious fix, see attached patch.

More seriously: I am not familiar with any part of the kernel code, so
it's very unlikely that I'll find the time and motivation to delve into
it and come up with a patch.  But if you could use some other kind of
help (e.g. some things to test, some printks to add to the code to
collect various kinds of data, ...), please holler,


        Stefan

Re: Slow b43 with 2.6.25.9 on an asus wl-700ge home-router

[Michael Buesch]

On Wednesday 09 July 2008 17:43:49 Stefan Monnier wrote:
> >> Any idea what might be going on?
> > Yeah well.  It's a bug somewhere.
> 
> The scary part is that there's only Free Software involved, AFAICT.
> That *should* be bug-free, shouldn't it?

<inhuman mode>
Either my sense of irony currently is out of order, or this is the
most stupid question I did _ever_ see.
</inhuman mode>

> > I didn't have time to track it down, yet.
> 
> Does that mean that you know about the problem and can reproduce it?

I can reproduce it, but I have no idea why it happens.

-- 
Greetings Michael.

Re: Slow b43 with 2.6.25.9 on an asus wl-700ge home-router

[Stefanik Gábor]

On Wed, Jul 9, 2008 at 7:50 AM, Stefan Monnier <monnier@iro.umontreal.ca> wrote:
> I finally started to use the b43 driver on my home-router and am happy
> to have it working at all (with WPA), but I notice that the speed is
> pretty terrible: I cannot seem to get more than 100KB/s out of it (I
> use it as a personal web proxy, so it ends up slowing down my
> web-surfing :-( ).
>
> Originally "iwconfig" told me that the bit rate was 2Mb/s (and even
> that should allow me to get a bit more than 100KB/s).
> After "iwconfig wlan0 rate 54M", the result is the same (except that
> "iwconfig" tells me the bit rate is 54Mb/s).
>
> More specifically, iwconfig tells me things like:
>
> wlan0     IEEE 802.11  ESSID:"test"
>          Mode:Managed  Frequency:2.457 GHz  Access Point: 00:10:30:C0:50:50
>          Bit Rate=54 Mb/s   Tx-Power=27 dBm
>          Retry min limit:7   RTS thr:off   Fragment thr=2352 B
>          Link Quality=95/100  Signal level:-54 dBm  Noise level=-63 dBm
>          Rx invalid nwid:0  Rx invalid crypt:0  Rx invalid frag:0
>          Tx excessive retries:0  Invalid misc:0   Missed beacon:0
>
> which seems to indicate that the reception is indeed good.
> Any idea what I might want to check?
>
> I did notice that my dmesg says things like
> "received packet with  own address as source address".  This seems
> related to my use of bridging, but:
> 1 - I have no bridging loop (actually I unplugged all ethernet cables,
>    so the only active network interface in the bridge is wlan0).
> 2 - taking wlan0 out of the bridge eliminates those messages, but
>    doesn't improve the bandwidth.
>
> Any idea what might be going on?
>
>
>        Stefan
>
> --
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>

Can you see "PHY transmission error" messages in dmesg? If you get
those, then that's a known bug.

-- 
Vista: [V]iruses, [I]ntruders, [S]pyware, [T]rojans and [A]dware. :-)

Re: Slow b43 with 2.6.25.9 on an asus wl-700ge home-router

[Stefan Monnier]

> Can you see "PHY transmission error" messages in dmesg? If you get
> those, then that's a known bug.

No, there's no "PHY" in dmesg.


        Stefan

Re: Slow b43 with 2.6.25.9 on an asus wl-700ge home-router

[Larry Finger]

Stefan Monnier wrote:
> I finally started to use the b43 driver on my home-router and am happy
> to have it working at all (with WPA), but I notice that the speed is
> pretty terrible: I cannot seem to get more than 100KB/s out of it (I
> use it as a personal web proxy, so it ends up slowing down my
> web-surfing :-( ).
> 
> Originally "iwconfig" told me that the bit rate was 2Mb/s (and even
> that should allow me to get a bit more than 100KB/s).
> After "iwconfig wlan0 rate 54M", the result is the same (except that
> "iwconfig" tells me the bit rate is 54Mb/s).
> 
> More specifically, iwconfig tells me things like:
> 
> wlan0     IEEE 802.11  ESSID:"test"  
>           Mode:Managed  Frequency:2.457 GHz  Access Point: 00:10:30:C0:50:50   
>           Bit Rate=54 Mb/s   Tx-Power=27 dBm   
>           Retry min limit:7   RTS thr:off   Fragment thr=2352 B   
>           Link Quality=95/100  Signal level:-54 dBm  Noise level=-63 dBm
>           Rx invalid nwid:0  Rx invalid crypt:0  Rx invalid frag:0
>           Tx excessive retries:0  Invalid misc:0   Missed beacon:0
> 
> which seems to indicate that the reception is indeed good.
> Any idea what I might want to check?
> 
> I did notice that my dmesg says things like
> "received packet with  own address as source address".  This seems
> related to my use of bridging, but:
> 1 - I have no bridging loop (actually I unplugged all ethernet cables,
>     so the only active network interface in the bridge is wlan0).
> 2 - taking wlan0 out of the bridge eliminates those messages, but
>     doesn't improve the bandwidth.
> 
> Any idea what might be going on?

What model is your card? Please post the output of 'dmesg | grep b43'.

With the current versions of mac80211, the rate-setting mechanism is very good. 
If you force a high rate, i.e. with 'iwconfig ... 54M', you run the risk of 
increasing your error rate causing many more retransmits, and might reduce the 
throughput. That may not be happening here, but I wonder why the rate capped at 
2M. Incidentally, the quality numbers for my BCM4312 located about 2m from the 
AP are "Link Quality=93/100  Signal level:-37 dBm  Noise level=-71 dBm". My Link 
Quality is lower than yours, but S/N is much better - not that any of those 
numbers have much validity. My transmit throughput is consistently over 2 Mbs, 
but I'm not bridging. Roughly 6 months ago, I did set up routing, but that was 
using iptables, not a formal bridge device. That configuration had full speed.

If you shut down the bridge, what speed do you get?

Larry


Larry

Re: Slow b43 with 2.6.25.9 on an asus wl-700ge home-router

[Stefan Monnier]

> What model is your card? Please post the output of 'dmesg | grep b43'.

   b43-phy0: Broadcom 4318 WLAN found
   b43-phy0 debug: Found PHY: Analog 3, Type 2, Revision 7
   b43-phy0 debug: Found Radio: Manuf 0x17F, Version 0x2050, Revision 8
   b43-phy0 debug: DebugFS (CONFIG_DEBUG_FS) not enabled in kernel config
   input: b43-phy0 as /devices/virtual/input/input0
   b43-phy0: Loading firmware version 410.2160 (2007-05-26 15:32:10)
   b43-phy0 debug: Chip initialized
   b43-phy0 debug: 32-bit DMA initialized
   Registered led device: b43-phy0::radio
   b43-phy0 debug: Wireless interface started
   b43-phy0 debug: Adding Interface type 2
   b43-phy0 debug: Removing Interface type 2
   b43-phy0 debug: Wireless interface stopped
   b43-phy0 debug: DMA-32 rx_ring: Used slots 0/64, Failed frames 0/0 = 0.0%, Average tries 0.00
   b43-phy0 debug: DMA-32 tx_ring_AC_BK: Used slots 0/128, Failed frames 0/0 = 0.0%, Average tries 0.00
   b43-phy0 debug: DMA-32 tx_ring_AC_BE: Used slots 0/128, Failed frames 0/0 = 0.0%, Average tries 0.00
   b43-phy0 debug: DMA-32 tx_ring_AC_VI: Used slots 0/128, Failed frames 0/0 = 0.0%, Average tries 0.00
   b43-phy0 debug: DMA-32 tx_ring_AC_VO: Used slots 0/128, Failed frames 0/0 = 0.0%, Average tries 0.00
   b43-phy0 debug: DMA-32 tx_ring_mcast: Used slots 0/128, Failed frames 0/0 = 0.0%, Average tries 0.00
   input: b43-phy0 as /devices/virtual/input/input1
   b43-phy0: Loading firmware version 410.2160 (2007-05-26 15:32:10)
   b43-phy0 debug: Chip initialized
   b43-phy0 debug: 32-bit DMA initialized
   Registered led device: b43-phy0::radio
   b43-phy0 debug: Wireless interface started
   b43-phy0 debug: Adding Interface type 2

> With the current versions of mac80211, the rate-setting mechanism is very
> good. If you force a high rate, i.e. with 'iwconfig ... 54M', you run the
> risk of increasing your error rate causing many more retransmits, and might
> reduce the throughput.

Yes, that's what I'd expect.  I only did it to see if it made any
difference, and as a matter of fact, it makes no difference: I get the
same 90-92 KB/s on average (averaged over a 3.6MB http transfer).

> That may not be happening here, but I wonder why the
> rate capped at 2M. Incidentally, the quality numbers for my BCM4312 located
> about 2m from the AP are "Link Quality=93/100  Signal level:-37 dBm  Noise
> level=-71 dBm". My Link Quality is lower than yours, but S/N is much
> better - not that any of those numbers have much validity.

I've moved the machine to get a better signal, it now says:

wlan0     IEEE 802.11  ESSID:"MM"  
          Mode:Managed  Frequency:2.457 GHz  Access Point: 00:18:3F:CB:5A:59   
          Bit Rate=2 Mb/s   Tx-Power=27 dBm   
          Retry min limit:7   RTS thr:off   Fragment thr=2352 B   
          Encryption key:ADAD-D31C-F6E7-1781-F165-21F0-A155-44C2-03C4-0D43-167C-05E8-C6EE-B111-1125-F1CD [2]
          Link Quality=114/100  Signal level:-41 dBm  Noise level=-64 dBm
          Rx invalid nwid:0  Rx invalid crypt:0  Rx invalid frag:0
          Tx excessive retries:0  Invalid misc:0   Missed beacon:0

I.e. it's not just better: it's more than perfect ;-)
But the bandwidth is still the same 90-92KB/s.

> My transmit throughput is consistently over 2 Mbs,

All the other wireless clients I've used around here (other
broadcomm-based home routers, rt73usb dongles, and iwl3945, hostap,
madwifi laptops), I basically always get pretty much the same bandwidth,
of around 10Mb/s, so there's definitely something odd going on here.

> but I'm not bridging.  Roughly 6 months ago, I did set up routing, but
> that was using iptables, not a formal bridge device. That
> configuration had full speed.

As mentioned, I get the same result without bridging.

> If you shut down the bridge, what speed do you get?

Same old 90-92KB/s.


        Stefan


PS: The code I use is the one from the OpenWRT svn repository.